Underwater colonoscopy: what it is and how it differs from standard colonoscopy
Colonoscopy remains the gold standard for detecting and monitoring conditions affecting the large bowel, such as colorectal cancer, polyps, and inflammatory bowel disease. It allows for accurate visualisation of the colonic mucosa and biopsy, as well as the removal of any polyps. It has the potential to reduce the risk of colorectal cancer. However, advances in technique have led to refinements that can improve patient comfort and the quality of the procedure. One such technique is the underwater colonoscopy, which Professor Sauid Ishaq has introduced in UK, as featured in the Daily Mail.
What is a colonoscopy?
A colonoscopy is a procedure used to examine the inside of the large intestine (colon and rectum) using a flexible tube with a camera at the end, called a colonoscope. It allows direct visualisation of the bowel lining and is widely used for:
- Investigating symptoms such as rectal bleeding, abdominal pain, persistent diarrhoea, or unexplained weight loss
- Screening and surveillance for bowel cancer and polyps, especially in individuals over 50 or with a family history of colorectal cancer
- Monitoring chronic conditions, including ulcerative colitis and Crohn’s disease
Colonoscopy is a safe and routine procedure, but the experience can vary depending on the technique used.
What is an underwater colonoscopy?
In a standard colonoscopy, the endoscopist inflates the bowel using air or carbon dioxide (gas) to insufflate and expand the lumen to allow clear visualisation and safe navigation of the colonoscope. WE is a standardised insertion technique in which infused water is removed mainly during insertion to allow progression in clear water, without any gas insufflation and removing all residual gas pockets, trying to facilitate scope progression and caecal intubation; achieve the best possible degree of colon cleanliness. Underwater colonoscopy is new technique in which water in infused through the scope to facilitate scope progression without using any gas. Infused water is simultaneously removed (water exchange)..This water-based technique offers several advantages:
- Improved patient comfort, as water causes less stretching and bloating compared to gas
- Better visual clarity, especially when the bowel preparation isn’t perfect, water exchange during colonoscopy improves colon cleanliness.
- Higher detection rates for smaller or flatter polyps. This has been confirmed with scientific studies that underwater colonoscopy is associated with higher adenoma detection rate (polyp with potential to grow into cancer) than gas insufflation colonoscopy
- Reduced need for sedation, making recovery quicker and lowering risks for some patients
Who is suitable for an underwater colonoscopy?
Most individuals who are eligible for a standard colonoscopy are also suitable for the underwater approach. This includes those undergoing the procedure for:
- Routine bowel cancer screening
- Investigation of lower gastrointestinal symptoms
- Follow-up after previous polyp removal or bowel surgery
It may be particularly beneficial for patients who:
- Are anxious about discomfort during the procedure
- Have had incomplete or difficult colonoscopies in the past
- Have conditions that increase sensitivity to bowel distension
What happens during an underwater colonoscopy?
The preparation for an underwater colonoscopy is the same as for a standard one. Patients are asked to follow a bowel cleansing regimen the day before to ensure the colon is clear of any residue. On the day of the procedure, the patient may receive a light sedative or pain relief if needed.
During the procedure, the endoscopist infuses water into the colon through the colonoscope to gently open the bowel lumen. Gas (air or carbon dioxide) is completely switched off. The water acts as a medium that allows for a smoother passage of the scope, often resulting in less discomfort than traditional air insufflation. Infused water if simultaneously aspirated through the scope, a technique called water exchange.
Once the scope reaches the end of the colon (Caecum), most of the water is already aspirated out, and if necessary, carbon dioxide is used for the withdrawal phase. This is the stage where the endoscopist thoroughly examines the bowel lining and removes any suspicious growths or polyps for testing. The procedure usually takes 20 to 40 minutes, depending on findings and the patient’s anatomy. Recovery is generally swift, and most patients are able to return to their usual activities on the same day..
In this video, you can see an example of the underwater colonoscopy procedure.
Professor Ishaiq works closely with international experts on this technique and is widely published. He has carried out live demonstrations both nationally and abroad.